Toxicological evaluation by in vitro and in vivo assays of an aqueous extract prepared from Echinodorus macrophyllus leaves

Toxicity of an aqueous extract prepared from Echinodorus macrophyllus dried leaves, a plant used in folk medicine to treat inflammation and kidney mal functions, was estimated by different bioassays. Mutagenicity of the aqueou s extract was evaluated in the Salmoella/microsome assay (TA97a, TA98, TA10 0 and TA102 strains), with or without metabolic activation. No mutagenic ac tivity (lyophilized extract tested up to 50 mg/plate) could be detected to any of the tester strain. Furthermore, no cytotoxic effect has been observe d when a crude extract of E. macrophyllus (up to 7.5 mg/ml) was tested on t he exponential growth of hepatoma and normal kidney epithelial cells in cul ture. Toxicity of E. macrophyllus was also evaluated in male Swiss mice aft er 6 weeks of continuous ingestion of the aqueous extract in drinking water . Average daily ingested doses were 3, 23 and 297 mg/kg for a lyophilized e xtract, and 2200 mg/kg for a crude extract, with dose two being equivalent to the daily dose recommended to humans. At the end of the treatment, all a nimals revealed a deficit in final body weight ranging from 5 to 47%. Bioch emical analysis of the plasma revealed some minor alterations indicating su bclinical hepatic toxicity. Genotoxic effect on liver, kidney and blood cel ls has been also evaluated by the comet assay, being negative to liver and blood cells. However, DNA analyses of the kidney cells detected some genoto xic activity for the highest dose tested of E. macrophyllus extract, either lyophilized or crude. On the other hand, exposure dose of 13 mg/kg, equiva lent to the daily dose recommended to humans, did not revealed any genotoxi c effect and hence this herb seems to be safe to human organism. (C) 2000 E lsevier Science Ireland Ltd. All rights reserved.